The mechanical properties and dielectric properties of film specimens from cyanoethylated wood (CE-wood) which is a mixture of CE-(cellulose, hemicellulose, and lignin) were investigated and compared with those of cyanoethylated cellulose (CEC). From the dynamic mechanical measurement for CE-wood, it was observed distinctively that the segmental motions of the main chains were restrained by lignin. But these restraints were released with chlorination of CE-wood. The dynamic behavior for chlorinated CE-wood was similar to that for CEC. It was found that the CE-wood was plasticized effectively by blending with cyanoethylated poly(vinyl alcohol) (CE-PVA). The dynamic and static modulus of CE-wood decreased with increasing the CE-PVA fraction in the blended film, and the change of tensile strength at break for the CE-wood polyblends showed a maximum value at the CE-PVA fraction of ca. 40%. It was found that CE-wood which contained lignin showed very high values of dielectric constant comparable to those of CEC which was well known to be a high-performance dielectric materials. These dielectric properties were attributed to the segmental motion of the side chains, and it was tough that the behavior of the side chain was not so much influenced by the lignin as that of the main chain. CE-wood film specimens could be drawn to threefold the initial length in acetone aqueous solution. The degree of orientation measured by optical method increased rapidly at the early stage of drawing. The Young's modulus and the tensile strength at break of the high-drawn specimen increased to as much as three or four times those of the undrawn one, and the elongation at break changed little.